Depth control

ABSTRACT

1. Apparatus for maintaining an underwater device at a substantially predetermined depth in water, comprising; gas release means including a valve body, a valve seat movable relative to the valve body, a balloon attached to the valve body and to said device, an umbrella attached to the valve seat adapted to move same relative to the valve body in accordance with velocity of the apparatus in a generally vertical direction, means for generating gas within the balloon, said gas release means communicating with the inside of the balloon, a valve cooperating with the valve seat, hydrostatic pressure responsive means for moving said valve relative to the valve body and valve seat in accordance with hydrostatic pressure, the construction and arrangement being such that the amount of gas released from the balloon by the gas release means is a function of said velocity and pressure.

United States Patent [1 1 Gogolick et a1.

1 1 DEPTH CONTROL [751 Inventors: Roland M. Gogolick. Arlington;

Richard L. Brown. Lexington, both of Mass. William .1. Finney.Washington. DC

[73] Assignee: The United States 01 America as represented by theSecretary of the Navy, Washington. DC.

[22] Filed: Nov. 26, 1947 121] Appl. No.: 788,106

[52] U.S.Cl. 9/8 R. 102/14, 114/16E [51] Int. Cl. .1 1363b 45/08, B63b45/01) [58] Field of Search 9/8; 102/14 [50] References Cited UNITEDSTATES PATENTS 952.450 3/1910 Leon 102/14 1120.621 12/1914 Lindmark 1 .1102/14 1.379,273 5/1921 Meden 102/14 1.440.596 1/1923 Hammond. Jr.102/14 2.069.783 2/1937 Stevens l, 137/139 E 2.328.916 9/1943 LeComte9/8 2.430.698 11/1947 Allen l l .1 9/8 2.463.921 3/1949 Titcomb 137/139E FOREIGN PATENTS OR APPLICATIONS 24.821 1914 Great Britain 102/14 Feb.11,1975

38.603 3/1915 Sweden 102/14 Primary Iivunu'nur-Benjamin A. BorcheltAmi-mm E.\u!nim'rThumas H. Webb Armrmiv. Agent. or Firm- R.S. Sciascia.1",. Johnston EXEMPLARY CLAIM 1. Apparatus for maintaining an underwaterdevice at a substantially predetermined depth in water, compris ing; gasrelease means including a valve body. a valve seat movable relative tothe valve body, a balloon attached to the valve body and to said device,an umhrella attached to the valve seat adapted to move same relative tothe valve body in accordance with velocity of the apparatus in agenerally vertical direction. means for generating gas within theballoon. said gas release means communicating with the inside of theballoon, a valve cooperating with the valve seat. hydrostatic pressureresponsive means for moving said valve relative to the valve body andvalve seat in accordance with hydrostatic pressure. the construction andarrangement being such that the amount of gas released from the balloonby the gas release means is a function of said velocity and pressure.

6 Claims, 6 Drawing Figures PATENTEUFEB' 3.864.772

SHEET 10F 3 FIG. 2

gwoa/wtow ROLAND M. 6060!. 10K RICHARD L. BROWN WILLIAM J. FINNEY m,JQwK/MH PATENTED FEB] 1 I975 SHEET 2 8F 3 a wumvfw ROL AND M. GOGOL 16KRICHARD L. BROWN PATENTEB FEB! 1 I975 SHEET 3 OF 3 FIG. 5

grwc/wiw ROLAND M. G'OGOLIGA RICHARD L. BROWN WILLIAM J. FINA/E) DEPTHCONTROL This invention pertains generally to apparatus for maintaining adevice under water at a fixed depth. More particularly it relates to adepth control for maintaining an expendable underwater device at a fixeddepth for a predetermined time.

In naval tactics several potent weapons have been de signed with a viewto detecting and attacking submarines. Some of these weapons depend fortheir efficacy on the noise produced and emitted by the submarines. As adefensive measure in aid of the submarine. it has been proposed toutilize a device that may be dropped by aircraft, surface vessels, andsubmarines, and that will produce sound for the purpose of confusing theattacker. The advantages of such a decoy will be obvious.

In order to simulate the sound of a submarine and to effectively serveas a decoy, it is necessary that the noisemaker operate at apredetermined depth. For example, in a preferred form of noisemaker,which is adapted to be ejected from a submarine from depths as great as400 feet, the device rises to its operating depth of 40 feet and isdesigned to remain at that depth for to l2 minutes, during which time itemits its noise; thereafter, the assembly sinks to the bottom and leavesno trace.

In general, the decoy or noisemaker may comprise an explosive stack inthe form ofa cylinder. Detonation of the explosive elements willgenerate the desired signals. The upper portion of this cylinder isattached to the lower portion of another cylinder that contains thedepth control device for propelling the noisemaker to a predetermineddepth and for maintaining that depth.

The depth control device comprises a strong airtight fabric balloon. Atthe proper time this balloon is subjected to the action of the seawaterthat enters through apertures made for that purpose. Within the depthcontrol cylinder is a chemical that is designed to react with water togenerate a buoyant gas. In a preferred form of the invention this gas ishydrogen. The device is so designed that sufficient hydrogen isgenerated to impart positive buoyancey to the decoy or noisemaker tobring the noisemaker to a desired depth under water and to maintain thatdepth for a predetermined time. During this interval of equilibrium thenoisemaker will operate to send out the desired signals, and at thecompletion of its mission the whole device will sink to the bottom ofthe sea.

The invention will be more clearly understood with the aid of theaccompanying drawings.

In these drawings:

FIG. l is an elevation of the complete device comprising the depthcontrol and the noisemaker;

FIG. 2 is an elevation of the device during knock-off, that is, duringthe process when the balloon is emerging from its container;

FIG. 3 is an elevation of the balloon just after knockoff;

FIG. 4 is a schematic view of the depth control device in itsequilibrium position;

FIG. 5 is an enlarged view, partially in section, of the depth controldevice;

FIG. 6 is an elevation, partially in section, of the gas release valve.

The elements constituting the depth control are enclosed in a rigidsealed metallic container 10. The signal generator or noisemaker isenclosed in a cylindrical stack H. The upper part of the stack ll issecured to the bottom of the container 10.

Within the container 10 and bearing against the inner wall thereof aretwo cylindrical half shells 13 and 14. These half shells l3 and I4 whenassembled together form a complete open-ended cylinder. They are notattached to each other or to the container l0 but are held in theirposition against the inner wall of the container 10 by a flat spring 15at the lower end ofthe half shells l3 and 14.

in the space within the half shells l3 and M are normally positioned acollapsed balloon l6 and a collapsed supporting umbrella 17. For thepurpose of this invention it has been found that a material made of neoprene-impregnated Nylon fabric is eminently suitable for the balloon 16and the umbrella [7. A large proportion of the space within the balloonto is filled with a mass 21 of ground calcium hydride. It is a propertyof this compound that when it mixes with water it reacts rapidly to formcalcium hydroxide and hydrogen gas, in accordance with the followingequation:

Within the balloon 16, there is, in addition to the ground calciumhydride 2l, a stick 29 of the same chemical, calcium hydride, in solidform. This stick 29 is positioned longitudinally of the device withinthe balloon H3.

The Nylon fabric of the balloon I6 is provided with several apertures34, and at the proper time, when the balloon is subjected to the actionof the seawater, sufficient hydrogen will be evolved from the groundcalcium hydride 21 to give a buoyant effect to the balloon and itscooperating structure. Due to its large effective surface, the groundcalcium hydride 21 will rapidly generate a relatively large quantity ofhydrogen gas. At the same time this ground calcium hydride 21 will ofcourse be consumed rapidly. It is desired to obtain a greater buoyanteffect initially so as to arrest the falling of the device toward thebottom of the sea subsequent to its launching. While the water isreacting with the ground calcium hydride 21, it is also reacting with aportion of the stick 29, but because of its smaller surface compared toits volume, the stick 29 will not generate hydrogen gas as rapidly asthe ground compound 21. By the time the ground calcium hydride 2l hasbeen consumed, sufficient hydrogen is coming from the stick 29 to givethe complete structure sufficient buoyancy at the predetermined depth toneutralize its gravitational effect and to maintain the entire assemblyin equilibrium.

The equilibrium effect is obtained by means of a valve 22 positionedbetween the balloon l6 and the umbrella 17. This valve 22 is so designedthat it releases the generated hydrogen gas at a rate just sufficient tomaintain the device at its operating depth, for example, 40 feet belowthe surface, and the total quantity of calcium hydride is sufficient tomaintain the depth for it) to l2 minutes, during which time the signalgenerator emits its signal. Thereafter. the assembly sinks to the bottomof the sea and leaves no trace.

The stack ll contains a noisemaker 23, and the noisemaker 23 is attachedto the balloon l6 by a rope or wire 24 of the proper length. This lengthis sufficient to insure safety to the balloon l6 and the noisemaker 23during the process of knock-off.

A fuze 26 leads from the center hole of the explosive stack ll to asmokeless powder charge 27 at the top of the metal container l0. lnorder to prevent burning of the balloon 16 by the fuze 26, the latter isinclosed in a flexible, varnish-impregnated Fiberglass tube 28.

When the assembled structure is discharged from a submarine, a triggerdevice on the submarine actuates an igniter to ignite the fuze 26. Whenthe charge 27 explodes, the container is shot away. and the hall"-shells l3 and 14 are forced apart by the spring 15. Water entering theballoon 16 through the apertures 34 will react with the ground calciumhydride 2], rapidly filling the balloon 16 with hydrogen and making thesystem positively buoyant.

At the same time, the weight of the explosive stack 11 pulls downwardlyon the bottom of the balloon 16 so that the balloon 16 turns topside up.The presence of the hydrogen gas making the balloon l6 positivelybuoyant, the depth control will rise. As it approaches the presetoperating depth, usually 40 feet, the valve 22 will begin to release thegas until the operating position and neutral buoyancy are reached.During this time the stick 29 of calcium hydride reacts with the waterto generate hydrogen continuously at a slow rate. The gas will bereleased just fast enough through the valve 22 to maintain stability anddepth. If the device gets above its preset operating depth, the excessgas will be released and the device will fall to its equilibriumposition. After ten to twelve minutes of constant-depth operation, thehydride stick 29 will be consumed and the device will fall to thebottom.

If the valve 22 did not release hydrogen at the proper time, the balloon16 would be inherently unstable, for it the depth control device startedto rise, the entrapped gas would become more buoyant and the devicewould rise still faster. Similarly, if the device should start to fall,the gas would become less buoyant and the device would fall continuouslyfaster. Because a buoyancy-operated system is inherently unstable. thecontrol system must supply a series of corrections, that is, it mustreduce the net buoyancy to negative after it has become positive, thenincrease it to positive after it has become negative. The simplestmechanism for accomplishing this is to combine with the gas container apressure-operated or depth-operated gas release valve and a continuousor controllable gas source. For such a system, the net force is equal tothe net instantaneous buoyancy, and the resistance to motion isproportional to the velocity or some higher power of the velocity. Thevalve 22 is such that the velocityoperated component of control iscombined with the pressure-operated component. Depending upon therelative sensitivities, the pressure component can be considered as acorrection term to keep the slow drift to zero, or the velocitycomponent can be considered a correction term to keep the hunting to aminimum. Appropriate sensitivity ranges for these two components existthat reduce both the drift and the oscillations to negligible values.

The gas utilized for imparting positive buoyancy to the depth controldevice may be obtained from the reaction of lithium metal. lithiumhydride, or calcium hydride with sea water, to generate hydrogen. Ifdesired, another source may be used, such as compressed nitrogen orliquified carbon dioxide. The preferred source. for the size and weightof signal generator contemplated in this application, is calciumhydride.

To avoid the passage of the finely ground calcium hydride 2] into thevalve 22, a felt plug 3] is positioned at the bottom of the inlet of thevalve 22. A cord 32 connects the valve plug 3| with the signalsupporting means 24. The cord 32 is of such a length that the plug 31 isremoved from the valve 22 by the load 23 as the balloon 16 is stretchedafter knockoff. The support 24 may be in the form of a coil spring thatis initially positioned at the bottom of the container 10. The use ofsuch a spring will permit the exertion of a downward force on the bottomof the depth control device immediately after knockoff while at the sametime reducing to a minimum the possibility of damage due to the sud' denshock. The spring 24 is a constant such that the weight of the sounddevice hanging from it stretches it out to a sufficient length so as notto impair the sound output from the signal generator.

The holes 34 in the lower portion of the balloon l6 serve two functions.One is to allow the entrance of sea water to react with the calciumhydride, and the second is to permit the escape of excess gas andhydride mixture. Because of the rapid filling of the balloon 16 with thehydrogen gas from the mass 21, the gas must be released. during ascent,at a rate much greater than can be taken care of by the valve 22. Thisexcess gas is released through the holes 34 in the balloon 16.

As the depth control approaches or attains steady state operation, gaswill also be released through a plurality of holes 36 at the top oftheumbrella 17, at a rate just fast enough to offset the generation of gasby the stick 29 of calcium hydride. The net buoyancy of the balloon 16plus its attached load 23 is thus kept substantially zero, and the depthis kept constant.

The umbrella l7 serves the double purpose of damping vertical motion andof actuating the velocity component of the valve action. It is designedto provide a maximum of damping resistance in a minimum of storagevolume. The balloon I6 is large enough to float the load 23 and at thesame time retain enough water for the hydrogen generation. During therise to equilibrium depth, the water level in the balloon 16 isdetermined by the location of the holes 34 in the bottom of the balloonl6, and this water level is kept below the top of the calcium hydridestick 29. During steady state opera tion, the water within the balloonl6 rises to cover the stick 29.

The valve 22 will now be described in detail, with particular referenceto FIG. 6.

The lower portion of the valve comprises an inlet tube 41. The felt plug3| has a reduced portion that is adapted to fit within the opening ofthe inlet tube 41. The cord 32 extends through the plug 31 and itfastens to the top thereof by means ofa ring 42. An inlet screen 43positioned in the inlet tube 4] above the felt plug 31 aids inpreventing ingress of the ground calcium hydride 21. A plurality ofinlets 44 are thereby kept free for passage of the gas. After the gaspasses upwardly through the inlets 44, it flows along the outside of aSylphon bellows 45 and out between a valve ball 46 and its seat 57.Thence, the gas finds its way out of the depth control device throughthe holes 36.

The pressure component of control of gas release is supplied through theSylphon bellows 45 and the position of the valve ball 46. The Sylphon 45is pressure sealed at top and bottom and its stiffness is such that itshortens, for example, approximately 0.009 inches per lb. per sq. in.increase in pressure or 0.004 inches per ft. increase in depth of thedevice. The Sylphon assembly 45 is screwed into the valve body 47 bymeans of a reduced portion 48 extending from the bellows 45. Theposition of the reduced portion 48 of the Sylphon 45 in the valve body47 determines the operating depth. Consequently. adjustment of thereduced portion 48 provides a method of controlling the operating depth.

The velocity component of control of gas release is supplied through thelongitudinal motion of the valve seat 57. The valve seat 57 can travel.for example 0.l inches and is normally held at the center of this travelby two ring springs 49. The umbrella 17 is attached to the valve seat 57and the top of the umbrella 17 is held between two grooves 51 in theoutside of the seat 57 by means of two wire retaining rings 52. Thespring constant of the centering springs 49 is about 0.35 inches perkilogram. and the restoring force is approximately linear for forces upto about 0.15 kilograms. or for valve seat travel of about 0.04 inches.A force of 0.15 kilograms on the umbrella 17 corresponds to a velocityof about 0.2 ft. per second. As a result. an upward ve locity of about0.2 ft. per second at the equilibrium position of the depth controldevice will open the valve 22 as much as the displacement upwardly of IOfeet from the equilibrium position. The velocity component of controlbegins to be effective as soon as the device gets to within l0 feet ofits equilibrium position.

A preferred form of the invention is designed to be operated from asubmarine. When the complete device is ejected from the vessel theknock-off fuze 26 is ignited by the flash from a heat transfer plug atthe trigger end of the explosive stack 11. This heat transfer plug mayincorporate a S-second delay. The fuze 26 itself may have a period of 3seconds before knock-off. so that there is an approximate 8-second delaybetween triggering and knock-off. If ejected from a depth of about 400ft., the free fall of the device will be approximately 75 ft.additional, and the time of fall will be about ID or ll seconds. Afterknock-off the water will react with the ground calcium hydride 2] togenerate a large amount of hydrogen very rapidly. This will give thedevice positive buoyancy so that it will begin to rise. This rise mustbegin to take place before the device has reached an arbitrary depth of,say. 600 ft. as the maximum desirable depth. The hydrogen generated fromthe ground calcium hydride 21 is much greater than can be taken care ofby the valve 22 and the excess is released through the holes 34. Thestick 29 produces a steady gassing rate at the proper time, and thedepth control device obtains an equilibrium position, either by motionin one direction from its maximum depth. or by a series of dampedoscillations that are a result of the release of gas from the valve inaccordance with the pressure component of control of gas release and thevelocity component of control of gas release. The equilibrium positionis designed to be about 40 ft.. and the time ofoperation of the signalgenerator to be about l0 to 12 seconds. At the conclusion of thisperiod, all the calcium hydride has been consumed and the whole devicewill at once plummet to the bottom of the sea.

We claim:

1. Apparatus for maintaining an underwater device at a substantiallypredetermined depth in water. comprising; gas release means including avalve body, a valve seat movable relative to the valve body. a balloonattached to the valve body and to said device. an umbrella attached tothe valve seat adapted to move same relative to the valve body inaccordance with velocity of the apparatus in a generally verticaldirection. means for generating gas within the balloon. said gas releasemeans communicating with the inside of the balloon. a valve cooperatingwith the valve seat. hydrostatic pressure responsive means for movingsaid valve relative to the valve body and valve seat in accordance withbydrostatic pressure. the construction and arrangement being such thatthe amount of gas released from the balloon by the gas release means isa function of said velocity and pressure.

2. Apparatus in accordance with claim 1 wherein said pressure responsivemeans includes a bellows secured at one end to the valve body. its otherend carrying the valve.

3. Apparatus in accordance with claim 2 wherein said bellows isadjustably secured to the valve body to permit adjustment of saidpredetermined depth.

4. Apparatus comprising a pair of axially aligned members releasablysecured together in tandem relationship and adapted to be launched intowater through a submarine torpedo tube, one of said members being acontainer adapted to be blown apart to expose its contents to the waterand the other member being an underwater device, a flexible collapsedballoon disposed in said container. an umbrella within the containerattached to the balloon. means connecting the balloon and said othermember for suspending the latter from the former after said container isblown apart. means for blowing the container apart and releasing itscontents after the apparatus has been launched. chemical means withinthe balloon adapted to react with water and form a buoyant gas withinthe balloon. and valve means for releasing gas from the balloonconstructed and arranged to maintain the apparatus at a substantiallypredetermined depth in water. said umbrella adapted to damp movement ofthe apparatus in a generally vertical direction when it reaches itsequilibrium depth of submergence.

5. Apparatus in accordance with claim 4 wherein said umbrella isconnected to said valve means for operating same in accordance withvelocity of the apparatus in said vertical direction.

6. Apparatus in accordance with claim 4 wherein said chemical meanscomprises a mass of particles adapted to rapidly form gas at a ratesufficient to maintain positive buoyancy, whereby the apparatusrelatively rapidly rises to its equilibrium depth, and another massadapted to form gas at a slower rate for maintaining the apparatus atthe equilibrium depth.

1. Apparatus for maintaining an underwater device at a substantiallypredetermined depth in water, comprising; gas release means including avalve body, a valve seat movable relative to the valve body, a balloonattached to the valve body and to said device, an umbrella attached tothe valve seat adapted to move same relative to the valve body inaccordance with velocity of the apparatus in a generally verticaldirection, means for generating gas within the balloon, said gas releasemeans communicating with the inside of the balloon, a valve cooperatingwith the valve seat, hydrostatic pressure responsive means for movingsaid valve relative to the valve body and valve seat in accordance withhydrostatic pressure, the construction and arrangement being such thatthe amount of gas released from the balloon by the gas release means isa function of said velocity and pressure.
 2. Apparatus in accordancewith claim 1 wherein said pressure responsive means includes a bellowssecured at one end to the valve body, its other end carrying the valve.3. Apparatus in accordance with claim 2 wherein said bellows isadjustably secured to the valve body to permit adjustment of saidpredetermined depth.
 4. Apparatus comprising a pair of axially alignedmembers releasably secured together in tandem relationship and adaptedto be launched into water through a submarine torpedo tube, one of saidmembers being a container adapted to be blown apart to expose itscontents to the water and the other member being an underwater device, aflexible collapsed balloon disposed in said container, an umbrellawithin the container attached to the balloon, means connecting theballoon and said other member for suspending the latter from the formerafter said container is blown apart, means for blowing the containerapart and releasing its contents after the apparatus has been launched,chemical means within the balloon adapted to react with water and form abuoyant gas within the balloon, and valve means for releasing gas fromthe balloon constructed and arranged to maintain the apparatus at asubstantially predetermined depth in water, said umbrella adapted todamp movement of the apparatus in a generally vertical direction when itreaches its equilibrium depth of submergence.
 5. Apparatus in accordancewith claim 4 wherein said umbrella is connected to said valve means foroperating same in accordance with velocity of the apparatus in saidvertical direction.
 6. Apparatus in accordance with claim 4 wherein saidchemical means comprises a mass of particles adapted to rapidly form gasat a rate sufficient to maintain positive buoyancy, whereby theapparatus relatively rapidly rises to its equilibrium depth, and anothermass adapted to form gas at a slower rate for maintaining the apparatusat the equilibrium depth.